Novel implementations of scatterometry for lithography process control

Littau, Michael E.; Raymond, Christopher J.; Gould, Christopher; Gambill, Christy

doi:10.1117/12.473490

Cited by 6 publications

(3 citation statements)

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“…In recent years, in order to accelerate the learning curve in new technological introduction, but also to develop metrology target structures more representative of the device, model-less strategy have been introduced in the metrology field [1] [2]. Indeed, raw measurements of ellipsometers, especially on real time mode, are in essence extremely sensitive to slight variation of thicknesses (down to some Angstrom), slight optical index variation (down to 0.01 variation in n values) and patterning details (shape, dishing…).…”

Section: This Work Has Received Funding From the Electronic Component...mentioning

confidence: 99%

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On the Fly Ellipsometry Imaging for Process Deviation Detection

Alcaire

Cunff

Soulan

et al. 2022

IEEE Trans. Semicond. Manufact.

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Spectroscopic ellipsometry is a very sensitive optical metrology technique commonly used in semiconductor manufacturing lines to accurately measure the thickness and refractive index of different layers present on specific dedicated metrology targets on the wafers. In parallel, optical defectivity techniques are widely implemented in production lines to inspect a significant amount of dies representative of the full wafer and detect physical and patterning defects. A new approach can then simply emerge which is to apply ellipsometry metrology techniques at a full or die wafer scale. This strategy, at the frontier between metrology and defectivity field is expected to bring solutions for certain types of process deviation. In our case, ellipsometry's optical response was collected on large areas of product wafers to capture specific deviations such as film properties, thickness, and patterning variation. This is an innovative strategy that relies on a model-less approach to detect process drifts, using ellipsometry's sensitivity to material properties and design architecture variations. In this paper, we will present this approach on three industrial cases.

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Section: This Work Has Received Funding From the Electronic Component...mentioning

confidence: 99%

“…For phase-modulated ellipsometer, the raw data gathered are the ellipsometry parameters Is and Ic, which values are bound between -1 and 1. These are linked to the usual ellipsometric angles Δ and Ψ through equations ( 1) and (2). 𝐼𝑠 = 𝑠𝑖𝑛 (2𝛹) 𝑠𝑖𝑛 (𝛥)…”

Section: On the Fly Ellipsometry Imaging For Process Deviation Detectionmentioning

confidence: 99%

On the Fly Ellipsometry Imaging for Process Deviation Detection

Alcaire

Cunff

Soulan

et al. 2022

IEEE Trans. Semicond. Manufact.

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“…Scatterometry has also been applied to measurement of 3D/doubly periodic structures 9 . Focus control methods using scatterometry have been reported using model-less 10 techniques. This research is focused on the use of optimized scatterometry test gratings to generate Bossung plots for an automated focus monitor to measure lithography best-focus and stage tilt.…”

Section: Introductionmentioning

confidence: 99%

Lithography tool qualification using angular scatterometry

et al. 2005

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Lithography process control remains a significant challenge in modern semiconductor manufacturing. Metrology efforts must overcome the complexity of the lithography process, as well as the number of process elements that contribute to overall process yield. One specific area of concern is lithography tool focus control. It is vital to control photolithography tool focus during the photoresist development step with a high degree of precision and accuracy. Furthermore, dose variations can compound the difficulty in determining focus. The lenses used in photolithography tools have a very limited depth of focus, so utmost precision is necessary. Tools that are in focus will result in sharper and better controlled features, while tools that are out of focus will result in improperly developed photoresist features.Angular scatterometry is a technology well-suited for lithography inspection and process control because it provides rapid measurement data and can be used for the measurement of resist line profiles. We report on model-based methods for focus control and their application towards photolithography control in a production setting. Topics of discussion include the effect of model parameter selection for focus metrics on focus curve quality and accuracy, as well as the effect of grating target design on focus sensitivity and accuracy. Measurement data using this focus technique in a production setting will be presented.

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